Conduit for electric conductors



UNTTnn STATES PATENT innen..

FRANK FULLER AND JOHN M. KINNEY, OF BOSTON, MASSACHUSETTS.

CONDUIT FOR ELECTRIC CONDUCTORS.

SPECIFICATION forming part of Letters Patent No. 554,631, dated February11, 1896.

Application met May`24,1895. seria1No.55o,5s1. momma.)

" 0 all whom it may concern:

Be it known that we, FRANK FULLER and JOHN M. KINNEY, of Boston, in thecounty of Suffolk and State of Massachusetts, have invented certain newand useful Improvements in Oonduits for Electric Conductors, of whichthe following is a specification;

This invention has relation to insulating conduits or tubes for electricconductors of the class in which the tube or conduit is not onlyperfectly insulatory in character but is armored or provided with alayer or member of steel or equivalent substance rendered fireproof andwaterproof both inside and outside, and it has reference also to the artof producing such conduits or tubes.

It is well known at the present time that in order to prevent thebreaking or cutting of the tubes by blows or by the driving of nails orscrews, as also to render them ireproof and proof against attacks byrodents and insects, the said tubes must be equipped with a metallic orequivalent armor of suificient strength to resist such blows orabrasions and attacks; but at the same time unless the metallic armor beseparated from the inclosed conductors by insulating material of somenature the tube or conduit will be rendered extremely dangerous, owingto the liability of the electric current being short-circuited in casethe conductor comes into contact with the armor; and, again, to preventthe presence of moisture in the tube and the consequent corrosion oroxidization of thearmor, it is necessary to cover the interior as wellas the exterior surface of the tube with waterproof material. For theprevention of the spread of re the tube or conduit must furthermore betreated with a non-combustible substance, so as to prevent its owndestruction or damage by lire. In addition to these things it is alsofrequently desirable that the .conduit should be equipped with two ormore its outer side in the novel manner hereinafter fully set forth.

Our invention further consists of a tube or conduit comprising in itsconstruction a metallic tube of steel to form the armor and having itsinterior surface covered with insulating ireproof material coated ortreated with such substances as will render it waterproof, and its outersurface inclosed in a wrapping of paper suitably treated.

It also consists of such a tube covered on its exterior surface with alayer of paper or other suitable material coated with an insulatingfireproof substance and coated with any suitable waterproof material.

It further consists of such a tube formed in two compartments suitablyinsulated from each other, each of which is adapted to receive one ofthe conductors forming an electric circuit; and the invention alsoconsists of the art of producing conductors of the kind above described,and in the features of construction which are hereinafter pointed outwith more particularity and set forth in the appended claims.

Reference is to be had to the annexed drawings and to the letters markedthereon, forming a part of this specification, the same lettersdesignating the same parts or features, as the case may be, whereverthey occur.

In the drawings, Figure l is a perspective view showing the first stepwhich may be performed in the process of making our improved electricconductors. Fig. 2 is a perspective view of a piece of our improvedelectric conductor, showing it completed and in different stages of itsformation. Fig. 3 is a View similar to Fig. 2, showing the invention asembodied in a structure containing two tubes or conduits. Fig. 4 is across-section of the tube shown in Fig. 3. Fig. 5 is aperspective viewof a modified form of the invention illustrated in Fig. 3. Fig.@illustrates diagrammatically a modification.

In carrying out our invention in the form illustrated in Figs. 1 and 2we take a strip a of sheet-steel or other equivalent material of desiredwidth and cover or coat the same with a compound or mixture of silicateof soda and mica, or treat it in an equivalent manner. We then take asheet or strip of paper b, wider than the metallic strip a, which hasbeen previously treated with the same com- IOO pound or mixture as thestrip a, and lay it upon or cement it to the strip a so that one edgewill match one edge of the said strip a, and so that the other edge willoverlap the said strip c, as is clearly shown in Fig. l, in which theoverlapping portion of the paper strip is lettered c.. The strip d soprepared is then bent so as to bring its longitudinal edges d togetherand form a tube of suitable shape, with the paper-covered face inside ofthe tube, all as is represented at c in Fig. 2. The overlapping portionc may now be wrapped several times about the tube, as indicated at f,and cemented or otherwise secured in place so as to keep it fromunwinding, and so as to hold the edges of the strip a together. Thestructure may then be coated or otherwise treated with a suitablewaterproof compound, as indicated at Z, in solid black. Under this modeof construction it will be seen that the overlapping part c of the paperstrip or sheet Z2, when the strip a is bent so as to form a tube, willproject from the inner to the out side between the meeting edges cl,from which line or point it may be wrapped around the tube, as hasalready been described; but the functions of the invention will not bechanged or the invention altered to a material extent if the innerlining were composed of a separate strip and the outer covering madeindependent thereof, and for some uses the waterproof coating Z may bedispensed with.

In case it is desired to form the conduit with two tubes two sheets amay be employed and each bent into a half-round form, as represented at7L, so that the meeting edges d will be opposite the one to the otherwhen the tubes are brought together, and so that the overlapping portionc of the sheet Z) will extend in opposite directions from said meetingedges and between the two tubes. rlhen by wrapping the overlapping partc around the two tubes from opposite lines or points the double-tubestructure will be formed as shown in Fig. et and as represented at]l inFig. 3.

Instead of wrapping the outside covering j upon the tubes, a-s shown inthe last-mentioned figures, strips of properly-prepared paper may bewound spirally upon the tubes,

as shown at 7.; in Fig. 5, in which case abinding strip or sheet g maybe wound and cemented on the wrapping-strip 71; to keep the latter fromunwinding.

It is preferable, though not essential, in cases where two or aplurality oi' tubes are embodied in the structure to place strips m, ofpaper, strawboard, or other similar insulatory material, between theouter opposing or adjacent metallic faces of the individual tubes, aswell as to place an edge portion l) of the winding sheet or strip l)therebetween, as is clearly shown in Figs. 3 and 4.

It is obvious that the form of the individual tubes is not of theessence of our invention, since they may be square, round, halt-round,or of other form, and that more than two individual tubes may beembodied in one conduit. Again, in the formation of the steel tube thelongitudinal edges may be brought close together, as is shown in most ofthe iigures of the drawings, or they may be left separated to a greateror less extent, as is represented in Fig. 6, wherein the steel tubes arebut half-round in cross-section, as though the two were made from asingle-sheet tube split longitudinally and centrally, the edges o ofeach individual tube abutting against the spacing or separating strips mand the edge portions 'a of the wrapping or winding sheet or sheets l).

In Figs. 3, 4, 5, and G the lining of the tubes is shown as separatefrom the winding-sheet, while in Figs. 1 and 2 the winding-sheet is acontinuation of the lining. It is obvious, however, that either methodmay be employed in all cases or that both maybe used circumstances orconvenience may suggest.

llaving thus explained the nature of the invention and described a wayof constructing and using the same, though without attempting to setforth all of the forms in which it maybe made or all of the modes of itsuse, it is declared that what is claimed isl. A conduit for electricconductors, con,- sisting of a sheet of metal bent to form a tube bybringing its longitudinal edges together and having its inner and outersides treated with an insulating and ireproof substance.

2. A conduit for electric conductors consisting of a sheet of metal bentto form a tube by bringing its longitudinal edges together, and having asheet of insulating iireprooi paper secured upon its inner side andprojecting between the said meeting' edges and wrapped around itsoutside.

3. A conduit for electric conductors, consisting of a sheet of metalbent toform a tube by bringing its longitudial edges together, andhaving a sheet of insulating iireprooi paper secured upon its inner sideand projecting between the said meeting edges and wrapped around itsoutside and the whole treated cxteriorly with a waterproof substance.

4. The art of forming electric conduits which consists in cement-ing toa strip of sheet metal a portion of a sheet of properly-treatedinsulating-paper or other suitable material, bending the sheet-metalstrip into the form of a tube with the portion of the paper strip notcemented thereto extending therefrom, and winding such extended portionof the paper strip about the tube, all as hcreinbefore set forth.

In testimony whereof we have signed our names to this specification, inthe presence oi' two subscribing witnesses, this lst day of May,

` FRANK FULLER.

J OIIN M. KINNEY. Witnesses ARTHUR W. CRossLn'r, C. C. STECHER.

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